Ajax的DropDrowList应用——改变一个drp会引起另一个drp的值改变

版权声明：Till good is better, but better best !My trying hard will go on!Please wait and see! https://blog.csdn.net/u012761373/article/details/45629199

通过Ajax技术对DropDrowList控件联动改变应用

改变一个DropDrowList会引起另一个DropDrowList的值改变：

Page Code：

<table>
            <tr>
                <th>省份</th>
                <td>
                    <asp:DropDownList ID="drpProvice" runat="server" 
                        onselectedindexchanged="drpProvice_SelectedIndexChanged" AutoPostBack="True">
                    </asp:DropDownList>
                </td>
                <th>城市</th>
                <td><asp:DropDownList ID="drpCity" runat="server">
                    </asp:DropDownList></td>
            </tr>
        </table>

Class Code：

protected void Page_Load(object sender, EventArgs e)
        {
			if (!IsPostBack)
			{
				InitData();
			}
        }
		
		protected virtual Int32 StringToInt32(string val, Int32 defaultVal)
		{
			int tmp = 0;
			if (Int32.TryParse(val, out tmp))
			{
				return tmp;
			}
			return defaultVal;
		}
		public SqlConnection Open()
		{
			string strConn = ConfigurationManager.ConnectionStrings["MySqlDataBase"].ConnectionString;
			SqlConnection conn = new SqlConnection(strConn);
			conn.Open();
			return conn;
		}
		public void Close()
		{
			SqlConnection conn = Open();
			conn.Close();
		}
		private void InitData()
		{
			ProviceBind();
			Citybind();
		}
		private void ProviceBind()
		{
			string strSql = "select * from Ajax_Provice";
			SqlConnection conn = Open();
			SqlDataAdapter da = new SqlDataAdapter(strSql, conn);
			DataSet ds = new DataSet();
			da.Fill(ds);
			drpProvice.DataSource = ds.Tables[0];
			drpProvice.DataTextField = "c_provName";
			drpProvice.DataValueField = "c_provId";
			drpProvice.DataBind();
			//drpTypeId.Items.Insert(0, new ListItem("全部", ""));

		}
		private void Citybind()
		{
			int temp = StringToInt32(drpProvice.SelectedValue, 0);
			string strSql = "select * from Ajax_City Where c_provId = {0}";
			strSql = string.Format(strSql, temp);
			SqlConnection conn = Open();
			SqlDataAdapter da = new SqlDataAdapter(strSql, conn);
			DataSet ds = new DataSet();
			da.Fill(ds);
			drpCity.DataSource = ds.Tables[0];
			drpCity.DataTextField = "c_city";
			drpCity.DataValueField = "c_provId";
			drpCity.DataBind();
			Close();
		}
		protected void drpProvice_SelectedIndexChanged(object sender, EventArgs e)
		{
			Citybind();
		}

当然只有这些代码，是不行的，要记住一点要把DropDrowList的属性 AutoPostBack设置为"True"，不然不会有联动的效果哦。
数据库图：